View source for OHPC-SSH-HOSTKEY-CHANGE-FIX


You may get the error below when trying to SSH to the new ELSA cluster from your Mac, PC or when using the <code>>_ELSA OpenHPC Cluster Shell Access</code> terminal in Open OnDemand.

<pre>
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@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
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IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:Tydfgvr4fQRlh2L/sqHu6gUR80O1DhDLBeL99HKaIQc.
Please contact your system administrator.
Add correct host key in ~/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in ~/.ssh/known_hosts:154
ECDSA host key for elsa.hpc.tcnj.edu has changed and you have requested strict checking.
Host key verification failed.
</pre>

To resolve the issue and remove the error message, follow the instruction below based on the platform from where you are running the SSH command.

=== Windows ===
You will most likely be prompted by your SSH/terminal program to confirm the change in the SSH host key fingerprint. Click the Ok/Confirm/etc. button to accept the new key.

=== Mac ===
Open a terminal window (you're probably already using the terminal window).<br>
Type the following before at the terminal prompts.
<pre>
ssh-keygen -R elsa.hpc.tcnj.edu
ssh-keygen -R 159.91.50.30
</pre>
Retry your SSH command again.<br>
You will probably be asked to accept/confirm the SSH host key fingerprint. Type <code>yes</code> and press the ENTER or RETURN key. This should only happen the first time after running the <code>ssh-keygen</code> commands.

=== Open OnDemand Web Portal ===
While this error doesn't prevent you from opening an <code>>_ELSA OpenHPC Cluster Shell Access</code> terminal window, you will get the error message each time. To get rid of that message, follow these steps.

Type the following at the Linux command prompt.
<pre>
ssh-keygen -R elsa.hpc.tcnj.edu
ssh-keygen -R 159.91.50.30
</pre>

Type <code>exit</code> and close the browser tab with the terminal. 
Open a new <code>>_ELSA OpenHPC Cluster Shell Access</code> terminal.<br>
You may see a message about adding a new host key. This should only happen the first time after running the <code>ssh-keygen</code> commands.